“My colleagues and I ran an experiment testing two different messages meant to convince thousands of resistant alumni to give.14 One message emphasized the opportunity to do good: donating would benefit students, faculty, and staff. The other emphasized the opportunity to feel good: donors would enjoy the warm glow of giving. The two messages were equally effective: in both cases, 6.5 percent of the stingy alumni ended up donating. Then we combined them, because two reasons are better than one. Except they weren’t. When we put the two reasons together, the giving rate dropped below 3 percent. Each reason alone was more than twice as effective as the two combined.”